Materials to be used in the packaging of snack foods and the like must have certain important technical properties. For instance, it is desirable that snack food packages be grease resistant, especially where items such as potato chips are to be contained therein. Another important property is spoilage inhibition. The bag must contain an effective oxygen barrier to prevent spoilage of the food by oxidation and it may be lined with opaque materials, which help to prevent spoilage by sunlight. Furthermore, there must be an effective moisture barrier to prevent damage to the food from moisture.
The successful snack package will have a certain degree of stiffness to protect the food and give the bag a desirable shape. In addition, the bond strength of the material must be such that the package will not rupture prematurely yet can be opened by the consumer with the exertion of a resonable amount of force. Also, the packaging material should be appropriate for decoration and for displaying information about the product, so that consumers will be attracted to it.
Certain widely used prior snack packaging materials have utilized glassine in combination with layers of plastic materials. One such material is known commercially as Rex-Lam 400P, marketed by Rexham Corporation, New York, N.Y. This material comprises an outside layer of polypropylene laminated with polyethylene to an inner layer of glassine. The glassine is coated on the inside with an emulsion of polyvinylidene chloride, which acts as a heat sealant. While the Rex-Lam 400P has appropriate properties for use in a snack food pacakage, it has become desirable to eliminate the glassine due to decreased availability and increased cost.